import java.util.ArrayList;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: WHY
 * Date: 2022-11-28
 * Time: 19:55
 */
public class TestDemo {
    public static void main(String[] args) {
        ArrayList  <Character>list=new ArrayList<>();
        String s1="Welcome to  bit";
        String s2="come";
        for(int i=0;i<s1.length();i++){
            char ch=s1.charAt(i);
            if(!s2.contains(ch+"")){//加这个""代表是字符串，或者用valueOf
                list.add(ch);
            }
        }
        System.out.println(list);
    }
}
